/*
* Function: freeSecureMemory()
*
* Description:
* Free a single page of secure memory.
*
* Inputs:
* p - The first virtual address of the secure memory to free.
* size - The amount of secure memory to allocate measured in bytes.
*
*/
void
freeSecureMemory (void) {
/*
* Get the current interrupt context; the arguments will be in it.
*/
sva_icontext_t * icp = getCPUState()->newCurrentIC;
/*
* Get the pointer address and size out of the interrupt context.
*/
unsigned char * p = (unsigned char *)(icp->rdi);
uintptr_t size = icp->rsi;
/*
* Verify that the memory is within the secure memory portion of the
* address space.
*/
uintptr_t pint = (uintptr_t) p;
if ((SECMEMSTART <= pint) &&
(pint < SECMEMEND) &&
(SECMEMSTART <= (pint + size)) &&
((pint + size) < SECMEMEND)) {
/*
* Zero out the memory.
*/
memset (p, 0, size);
/*
* Get the physical address before unmapping the page. We do this because
* unmapping the page may remove page table pages that are no longer
* needed for mapping secure pages.
*/
uintptr_t paddr = getPhysicalAddr (p);
/*
* Unmap the memory from the secure memory virtual address space.
*/
unmapSecurePage (get_pagetable(), p);
/*
* Release the memory to the operating system. Note that we must first
* get the physical address of the data page as that is what the OS is
* expecting.
*/
releaseSVAMemory (paddr, size);
}
return;
}
/*
* Function: release_frames()
*
* Description:
* Dequeue and free some number of frames in the frame cache queue.
*/
static inline void
release_frames(void) {
int i, max_nframe, nframe;
uintptr_t paddr;
/*
* Generate a suitable number not so big that triggers
* fill_in_frames() when calling frame_dequeue().
*/
max_nframe = frame_cache_used();
if (vg_random) {
/* A random number between 1 and current occupancy of frame cache queue */
nframe = random() % max_nframe + 1;
} else {
/* Minimum of a constant and current occupancy of frame cache queue */
nframe = max_nframe < MAX_FRAMES_PER_OP ? max_nframe : MAX_FRAMES_PER_OP;
}
for (i = 0; i < nframe; ++i) {
paddr = frame_dequeue();
releaseSVAMemory(paddr, X86_PAGE_SIZE);
}
}
